1. Field of the Invention
The present invention relates to a liquid crystal display device and an illuminating device.
2. Description of the Related Art
Recently, with respect to a display device, in place of a CRT (Cathode Ray Tube), a light-emitting-type plasma display panel or a non-light-emitting-type liquid crystal display device has been popularly used.
Out of these display devices, the liquid crystal display device uses a liquid crystal panel as a transmissive dimming element, and includes an illuminating device (also referred to as a backlight) which irradiates light to the liquid crystal panel on a back surface the liquid crystal panel. The liquid crystal panel forms an image by controlling transmissivity of light irradiated from the backlight.
One of the technical features of the liquid crystal display device lies in that the liquid crystal display device can be made thin compared to a CRT. Recently, there has been a demand for a liquid crystal display device with a further decreased thickness. Further, recently, with the advent of a backlight or an illuminating device which uses an LED (Light Emitting Diode) as a light source, there has been a demand for a thin illuminating device.
In view of such circumstances, for example, JP 2009-110811 A and JP 2009-32664 A disclose a technique on a side backlight in which an LED (Light Emitting Diode) is used as a backlight light source, the backlight light source is arranged on a side of a liquid crystal panel instead of aback surface of the liquid crystal panel, and light is irradiated from the back surface of the liquid crystal panel using a light guide plate.
By shortening a distance between the light guide plate and the light source, it is possible to enhance light utilization efficiency of the illuminating device (backlight). However, the light guide plate is warped or thermally expanded and hence, it is difficult to set the distance between the light guide plate and the light source to a value lower than a certain level. Accordingly, there has been a drawback that the further enhancement of the light utilization efficiency of the backlight is difficult.